Season the chuck roast with salt and black pepper.
Heat the olive oil in a large skillet over medium-high heat.
Sear the roast for 3–4 minutes per side, until browned.
Transfer the seared roast to the Crock Pot.
Add a splash of beef broth to the skillet and scrape up the browned bits from the bottom of the pan.
Pour the broth into the slow cooker.
Add the remaining beef broth, brown gravy mix, and onion soup mix.
Cover and cook on LOW for 8–9 hours or HIGH for 4–5 hours, until the beef is fork-tender.
Shred the beef and stir it into the rich gravy.
Serve over white bread with creamy mashed potatoes and additional gravy spooned over the top.
Optional Slow Cooker Step
For a simple recipe with minimal effort, skip searing the roast and place it directly into the Crock Pot with the broth, gravy mix, and onion soup mix.